/**
 * IK 中文分词  版本 5.0
 * IK Analyzer release 5.0
 * 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * 源代码由林良益(linliangyi2005@gmail.com)提供
 * 版权声明 2012，乌龙茶工作室
 * provided by Linliangyi and copyright 2012 by Oolong studio
 * 
 */
package org.wltea.analyzer.core;

import java.util.Arrays;


/**
 * 
 * 英文字符及阿拉伯数字子分词器
 */
public class LetterSegmenter implements ISegmenter {

    // 子分词器标签
    static final String SEGMENTER_NAME = "LETTER_SEGMENTER";
    // 链接符号
    private static final char[] Letter_Connector = new char[] { '#', '&', '+', '-', '.', '@', '_' };

    // 数字符号
    private static final char[] Num_Connector = new char[] { ',', '.' };

    /*
     * 词元的开始位置， 同时作为子分词器状态标识 当start > -1 时，标识当前的分词器正在处理字符
     */
    private int start;
    /*
     * 记录词元结束位置 end记录的是在词元中最后一个出现的Letter但非Sign_Connector的字符的位置
     */
    private int end;

    /*
     * 字母起始位置
     */
    private int englishStart;

    /*
     * 字母结束位置
     */
    private int englishEnd;

    /*
     * 阿拉伯数字起始位置
     */
    private int arabicStart;

    /*
     * 阿拉伯数字结束位置
     */
    private int arabicEnd;

    public LetterSegmenter() {
        Arrays.sort(Letter_Connector);
        Arrays.sort(Num_Connector);
        this.start = -1;
        this.end = -1;
        this.englishStart = -1;
        this.englishEnd = -1;
        this.arabicStart = -1;
        this.arabicEnd = -1;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wltea.analyzer.core.ISegmenter#analyze(org.wltea.analyzer.core.
     * AnalyzeContext)
     */
    public void analyze(AnalyzeContext context) {
        boolean bufferLockFlag = false;
        // 处理英文字母
        bufferLockFlag = this.processEnglishLetter(context) || bufferLockFlag;
        // 处理阿拉伯字母
        bufferLockFlag = this.processArabicLetter(context) || bufferLockFlag;
        // 处理混合字母
        bufferLockFlag = this.processMixLetter(context) || bufferLockFlag;

        // 判断是否锁定缓冲区
        if (bufferLockFlag) {
            context.lockBuffer(SEGMENTER_NAME);
        } else {
            // 对缓冲区解锁
            context.unlockBuffer(SEGMENTER_NAME);
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wltea.analyzer.core.ISegmenter#reset()
     */
    public void reset() {
        this.start = -1;
        this.end = -1;
        this.englishStart = -1;
        this.englishEnd = -1;
        this.arabicStart = -1;
        this.arabicEnd = -1;
    }

    /**
     * 处理数字字母混合输出 如：windos2000 | linliangyi2005@gmail.com
     * 
     * @param input
     * @param context
     * @return
     */
    private boolean processMixLetter(AnalyzeContext context) {
        boolean needLock = false;

        if (this.start == -1) {// 当前的分词器尚未开始处理字符
            if (CharacterUtil.CHAR_ARABIC == context.getCurrentCharType()
                    || CharacterUtil.CHAR_ENGLISH == context.getCurrentCharType()) {
                // 记录起始指针的位置,标明分词器进入处理状态
                this.start = context.getCursor();
                this.end = start;
            }

        } else {// 当前的分词器正在处理字符
            if (CharacterUtil.CHAR_ARABIC == context.getCurrentCharType()
                    || CharacterUtil.CHAR_ENGLISH == context.getCurrentCharType()) {
                // 记录下可能的结束位置
                this.end = context.getCursor();

            } else if (CharacterUtil.CHAR_USELESS == context.getCurrentCharType()
                    && this.isLetterConnector(context.getCurrentChar())) {
                // 记录下可能的结束位置
                this.end = context.getCursor();
            } else {
                // 遇到非Letter字符，输出词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.start, this.end - this.start + 1,
                        Lexeme.TYPE_LETTER);
                context.addLexeme(newLexeme);
                this.start = -1;
                this.end = -1;
            }
        }

        // 判断缓冲区是否已经读完
        if (context.isBufferConsumed()) {
            if (this.start != -1 && this.end != -1) {
                // 缓冲以读完，输出词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.start, this.end - this.start + 1,
                        Lexeme.TYPE_LETTER);
                context.addLexeme(newLexeme);
                this.start = -1;
                this.end = -1;
            }
        }

        // 判断是否锁定缓冲区
        if (this.start == -1 && this.end == -1) {
            // 对缓冲区解锁
            needLock = false;
        } else {
            needLock = true;
        }
        return needLock;
    }

    /**
     * 处理纯英文字母输出
     * 
     * @param context
     * @return
     */
    private boolean processEnglishLetter(AnalyzeContext context) {
        boolean needLock = false;

        if (this.englishStart == -1) {// 当前的分词器尚未开始处理英文字符
            if (CharacterUtil.CHAR_ENGLISH == context.getCurrentCharType()) {
                // 记录起始指针的位置,标明分词器进入处理状态
                this.englishStart = context.getCursor();
                this.englishEnd = this.englishStart;
            }
        } else {// 当前的分词器正在处理英文字符
            if (CharacterUtil.CHAR_ENGLISH == context.getCurrentCharType()) {
                // 记录当前指针位置为结束位置
                this.englishEnd = context.getCursor();
            } else {
                // 遇到非English字符,输出词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.englishStart, this.englishEnd - this.englishStart
                        + 1, Lexeme.TYPE_ENGLISH);
                context.addLexeme(newLexeme);
                this.englishStart = -1;
                this.englishEnd = -1;
            }
        }

        // 判断缓冲区是否已经读完
        if (context.isBufferConsumed()) {
            if (this.englishStart != -1 && this.englishEnd != -1) {
                // 缓冲以读完，输出词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.englishStart, this.englishEnd - this.englishStart
                        + 1, Lexeme.TYPE_ENGLISH);
                context.addLexeme(newLexeme);
                this.englishStart = -1;
                this.englishEnd = -1;
            }
        }

        // 判断是否锁定缓冲区
        if (this.englishStart == -1 && this.englishEnd == -1) {
            // 对缓冲区解锁
            needLock = false;
        } else {
            needLock = true;
        }
        return needLock;
    }

    /**
     * 处理阿拉伯数字输出
     * 
     * @param context
     * @return
     */
    private boolean processArabicLetter(AnalyzeContext context) {
        boolean needLock = false;

        if (this.arabicStart == -1) {// 当前的分词器尚未开始处理数字字符
            if (CharacterUtil.CHAR_ARABIC == context.getCurrentCharType()) {
                // 记录起始指针的位置,标明分词器进入处理状态
                this.arabicStart = context.getCursor();
                this.arabicEnd = this.arabicStart;
            }
        } else {// 当前的分词器正在处理数字字符
            if (CharacterUtil.CHAR_ARABIC == context.getCurrentCharType()) {
                // 记录当前指针位置为结束位置
                this.arabicEnd = context.getCursor();
            } else if (CharacterUtil.CHAR_USELESS == context.getCurrentCharType()
                    && this.isNumConnector(context.getCurrentChar())) {
                // 不输出数字，但不标记结束
            } else {
                // //遇到非Arabic字符,输出词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.arabicStart, this.arabicEnd - this.arabicStart + 1,
                        Lexeme.TYPE_ARABIC);
                context.addLexeme(newLexeme);
                this.arabicStart = -1;
                this.arabicEnd = -1;
            }
        }

        // 判断缓冲区是否已经读完
        if (context.isBufferConsumed()) {
            if (this.arabicStart != -1 && this.arabicEnd != -1) {
                // 生成已切分的词元
                Lexeme newLexeme = new Lexeme(context.getBufferOffset(), this.arabicStart, this.arabicEnd - this.arabicStart + 1,
                        Lexeme.TYPE_ARABIC);
                context.addLexeme(newLexeme);
                this.arabicStart = -1;
                this.arabicEnd = -1;
            }
        }

        // 判断是否锁定缓冲区
        if (this.arabicStart == -1 && this.arabicEnd == -1) {
            // 对缓冲区解锁
            needLock = false;
        } else {
            needLock = true;
        }
        return needLock;
    }

    /**
     * 判断是否是字母连接符号
     * 
     * @param input
     * @return
     */
    private boolean isLetterConnector(char input) {
        int index = Arrays.binarySearch(Letter_Connector, input);
        return index >= 0;
    }

    /**
     * 判断是否是数字连接符号
     * 
     * @param input
     * @return
     */
    private boolean isNumConnector(char input) {
        int index = Arrays.binarySearch(Num_Connector, input);
        return index >= 0;
    }
}
